As radial anti-friction bearings that can also be loaded with high axial forces, in practice, primarily single-row deep groove ball bearings are used, because these feature a uniform high radial and axial load capacity, low friction, and the highest rotational speed limits of all bearing types. These deep groove ball bearings are made, in a known way, from an outer bearing ring and an inner bearing ring, and also from a number of bearing balls arranged between the bearing rings as anti-friction bodies. Here, in the inside of the outer bearing ring and in the outside of the inner bearing ring, groove-shaped raceways are incorporated that are each limited by two axial rims and in which the bearing balls are guided at uniform distances relative to each other by a bearing cage. The use of the bearing balls in the deep groove ball bearing is here usually realized by the eccentric assembly method that has become known with DE 168 499 in which the two bearing rings are arranged eccentric to each other and the resulting free space between the bearing rings is filled with the bearing balls. Then the inner bearing ring is brought into the position concentric to the outer bearing ring under use of the elasticity of both bearing rings, so that the bearing balls can then be distributed uniformly in the raceways of the bearing rings and the bearing cage can be used.
In practice, however, it has been proven that such deep groove ball bearings are nevertheless subject to limits primarily with respect to the radial load capacity of the bearing due to the small maximum number of balls that can be installed. This number is dependent on the dimensions of the inner and the outer bearing rings and also the ball diameter. Therefore, in the past a plurality of solutions, such as, for example, an unsealed filling opening according to DE 151 483 arranged in opposite rims of the raceways of the outer and the inner bearing rings or a similarly constructed closable filling opening according to DE 24 07 477 A1, has been proposed with which an increase of the radial load capacity by deep groove ball bearings should be achieved by increasing the number of balls. These proposals, however, cannot be realized in practice due to numerous disadvantages.
In addition, another possibility for increasing the number of anti-friction bodies in a radial anti-friction bearing was known first through DE 311 317 and was improved by DE 43 34 195 A1. For these radial anti-friction bearings formed as single-row deep groove ball bearings, however, the anti-friction bodies are formed not by balls but instead by so-called spherical rollers that are formed with two side surfaces flattened symmetrically from a spherical base shape and also side surfaces arranged parallel to each other. The width of these spherical rollers between their side surfaces is here less than the distance between the radially opposing axial rims of the raceways in the bearing rings, so that filling the bearing with spherical rollers can be performed with the so-called axial mounting method in which the spherical rollers can be inserted in the axial direction into the bearing through the distance between the inner ring and the outer ring. If the center point of the bearing rollers is then located at the height of the raceway axis, the spherical rollers are turned once vertically and once horizontally by 90°, so that they can roll with their running surfaces in the raceways of the bearing rings.
However, despite the possibility of inserting these specially shaped spherical rollers axially into the bearing and thus filling the radial anti-friction bearings almost completely with a high number of anti-friction bodies that can be used for high radial loads, such a spherical roller bearing represents only a compromise with respect to the axial load capacity of the bearing. This is based on the fact that the spherical rollers can have a construction that is only relatively flat due to their ability to be inserted in the axial direction into the bearing only with a small width between their side surfaces and the raceways of the spherical rollers in the bearing rings, in order to be able to allow the rotation of the anti-friction bodies into their operating position, without producing too much radial play in the entire bearing. The relatively flat raceways of the spherical rollers, however, have the effect that, for adapting to an axially acting operational pressure angle acting in the axial direction, the spherical rollers provide too small a support surface due to axial tilting within their raceways, so that primarily the axial load capacity of such a spherical roller bearing is very low and such spherical roller bearings are thus unsuitable for high axial loads.
Therefore, for avoiding these disadvantages, it was proposed by the German Patent Application with the filing number 10 2005 014 556.6, that had not yet been published at the application date of the present patent application, to increase the width of the spherical rollers between their side surfaces to at least 70% of the diameter of their spherical base shape and to form the groove-shaped raceways of the spherical rollers in the bearing rings with a depth between 17% and 19% and also a width between 75% and 78% of the diameter of the spherical base shape of the spherical rollers, because in this way a total contact area of the spherical rollers to their raceways of approximately 45% of the periphery of the spherical base shape of the spherical rollers is produced, increasing both the radial and also the axial load capacity of the bearing, like the balls of conventional deep groove ball bearings have relative to their raceways in the bearing rings. However, because the distance between the rims defining the anti-friction body raceways of the inner and the outer bearing rings is smaller than the width of the spherical rollers, the setting of the spherical rollers into the radial anti-friction bearing must be performed again according to the known eccentric mounting method in which the spherical rollers are placed in a vertical position at the location of the greatest distance of the radially opposing rims of the two bearing rings arranged eccentric to each other perpendicular in the anti-friction body raceways and are shifted with their side surfaces contacting each other in the free space between the bearing rings. The flattened side surfaces of the spherical rollers, however, allow an increased number of anti-friction bodies to be mounted in the bearing compared with single-row deep groove ball bearings even with the eccentric mounting method. After filling the bearing with the bearing rollers, the inner bearing ring is then brought into the position concentric to the outer bearing ring, so that the spherical rollers are distributed on the reference circle of their raceways with a uniform distance to each other and can be pivoted by 90° into their operating position arranged longitudinal to the raceways, in order to then insert the bearing cage into the radial anti-friction bearing.
With such a spherical roller bearing formed in this way, it was indeed achieved that the spherical rollers have large contact surfaces to their raceways in the bearing rings and that the bearing can be equipped with a larger number of anti-friction bodies than conventional single-row deep groove ball bearings, so that, above all, the radial load capacity of the bearing increases relative to conventional deep groove ball bearings and the axial installation space and the weight of the bearing was reduced. Nevertheless, the increase of the axial load capacity of the bearing was relatively small, because the raceways of the spherical rollers that were indeed deepened were still too flat to completely support the spherical rollers for adaptation to the acting operating pressure angle through axial tilting within their raceways, so that such spherical roller bearings are still unsuitable for variable axial loads under extremely high operating pressure angles.